The present invention relates generally to valve assemblies for engine cylinders in an internal combustion engine, and more particularly to a moveable valve seat assembly that allows for selective gas flow control in a combustion chamber that is independent of piston position.
Existing internal combustion engines typically employ intake and exhaust poppet valves to regulate the gas flow to and from corresponding combustion chambers of an engine cylinder. The movement of the poppet valves may be carried out via traditional camshaft actuation means which depend on piston position, or by more recent camless approaches, which also depend on piston position.
In a typical engine, intake and exhaust poppet valves reciprocate into the combustion chamber to provide gas flow in preparation for combustion or to release exhaust gas after combustion. Generally, the poppet valves open by moving into the combustion chamber. The movement of the poppet valves is controlled by mechanical, electrical or hydraulic means. The poppet valve movement is timed to avoid contact with the reciprocating piston moving within the piston cylinder.
These methods, while workable, have drawbacks such as the possibility of valve-to-piston contact. Mistiming the opening of the poppet valves can lead to catastrophic valve-to-piston contact, which could destroy the engine. Thus, current poppet valve actuation designs are very sensitive to piston position. Also, the poppet valve is typically subjected to differential pressures on each side of the poppet valve. The poppet valve must overcome combustion chamber pressure or cylinder pressure to open into the combustion chamber. This requires large amounts of power to operate the valve train system, which opens the valves, to overcome cylinder pressure forces that are tending to oppose the opening of the valves. This results in high valve train system parasitic horsepower losses, which in turn lead to reduced engine efficiency and overall performance.
There is therefore a need for an apparatus and method that will allow for combustion chamber gas or air flow in a manner that is independent of piston position, thereby eliminating the potential valve-to-piston contact, and that substantially reduces power requirements to carryout gas flow to and from the combustion chamber, thereby resulting in improved engine efficiency and performance.
The present invention provides an apparatus and method for the selective control of gas flow to and/or from a combustion chamber through a moveable or retractable seat valve that is independent of piston position. The moveable or retractable seat valve eliminates the possibility of conventional valve-to-piston contact which results in complete freedom of valving events such that gas flow can be selectively initiated at any time during the engine cycle, or throughout the engine cycle if desired. Further, the moveable or retractable seat valve of the present invention is scalable and thus readily adaptable to internal combustions engines of various bore sizes. Also, the retractable seat valve is applicable in internal combustion engine applications that use diesel or gasoline as the primary fuel, or other alternative fuels, e.g. propane, methanol, compressed natural gas (CNG), etc.
In accordance with the present invention, there is provided a moveable or retractable seat valve (RSV) mechanism for controlling gas flow to and from a combustion chamber of an internal combustion engine that is used in conjunction with a cylinder head, a gas port, and a gas port opening into the combustion chamber. The retractable seat valve comprises a stationary seat disposed adjacent to or between the gas port opening to the combustion chamber. The stationary seat comprises a body portion that extends partially across the gas port opening and has a peripheral edge.
There is also a retractable seat disposed in the gas port. The retractable seat is selectively controlled for movement between an open position and a closed position in the gas the port. In the open position, the retractable seat allows gas flow between the gas port and the combustion chamber around the peripheral edge of the stationary seat. In the second closed position, the retractable seat is disposed in a sealing relationship with the peripheral edge of the stationary seat thereby preventing gas flow between the gas port and the combustion chamber.
The movement of the retractable seat may be selectively controlled by any of the well known techniques and devices available to those of skill in the art for controlling the movement of conventional poppet valves in camless applications or injection in electronic fuel injectors. These can include any combination of hydraulic, solenoid, electrical or mechanical means that may be selectively controlled by an engine electronic control module (ECM).
In accordance with the present invention, there is also provided a method for controlling gas flow in a combustion chamber of an internal combustion engine. The method comprises generating a command to actuate a moveable or retractable seat from an electronic control module; operating a valve actuator assembly and moving a seat valve actuator member; translating the movement of the seat valve actuator member to a retractable seat to move the retractable seat to a selected position between an open and closed position; and forming a gas passage between a retractable seat seating face and a stationary seat seating surface such that gas can flow in a controlled manner in the combustion chamber.
The following drawings and description set forth additional advantages and benefits of the invention. Other advantages and benefits will be obvious from the description and may be learned by practice of the invention.